Electromagnetic toggle filament tension monitoring device



July 21, 1970 J. E. BANCROFT ELECTROMAGNETIC TOGGLE FILAMENT TENSION MONITORINGDEVICE Filed April 4, 1967 m m E R7 55 DNWIIAITL a R s a. F

' ALARM FIG FIG. 2

FIG. 3

INVENTOR J. E. BANCROFT ATTORNEY United States Patent O 3,521,265 ELECTROMAGNETIC TOGGLE FILAMENT TENSION MONITORING DEVICE James E. Bancroft, Plainview, N.Y., assignor to Allied Control Company, New York, N.Y., a corporation of New York Filed Apr. 4, 1967, Ser. No. 628,404 Int. Cl. B65h 25/30; Htllh 36/ 00, 5/02 US. Cl. 340259 9 Claims ABSTRACT OF THE DISCLOSURE The armature of an electromagnetic toggle switch is switched from a first stable position to a second stable position to provide an electrical signal to actuate an alarm and/or a stop motion device when a preselected maximum torque is applied to a filament guide arm by the tension applied to a moving filament. An alarm and/ or stop motion device is also actuated by the filament guide arm when the tension applied to the moving filament falls below a predetermined value or a filament breakage occurs.

FIELD OF THE INVENTION The present invention relates to tension monitoring devices and more particularly to such devices utilized to monitor the tension applied to moving filaments.

Filament tension monitoring devices are utilized in many industries, e.g., the textile industry and the wire and cable industry, to monitor the tension applied to rapidly moving filaments as the filaments are transferred from spools or reels to processing machines. In the textile industry, for example, hundreds of yarns are simultaneously drawn from individual spools located in a creel to a beaming machine to produce a warp. It is essential in such operations that the tensions applied to the individual yarns be uniform or a defective warp can result. A tension monitoring device is utilized on each yarn to actuate an alarm if the tension applied thereto varies from a desired value. Similarly the breakage of a moving yarn which is followed by a loss of tension will be detected by such a monitoring device and the alarm actuated. The device may also control a stop motion device to halt the processing machine so that the cause of the change in tension or the yarn breakage can be corrected.

BACKGROUND OF THE INVENTION Many of the known filament tension monitoring devices monitor only for filament breakage, i.e., loss of tension. Many of the known devices which monitor for excessive tension as well as loss of tension are not adjustable for the different tensions required for various types and sizes of filaments. Those monitoring devices of the prior art which are adjustable to respond to different tensions require some individual manual manipulation to effect such adjustment and hence a plurality of such devices cannot be simultaneously adjusted from a common control.

Thus there is a need for a reliable, fast actuating filament tension monitoring device which will monitor for filament breakage as well as for excessive filament tension and which is readily adjustable to monitor for different predetermined excessive tensions to accommodate different types and sizes of filaments. There is also a need for such a filament tension monitoring device which may be adjusted simultaneously with a large number of like devices to monitor for different predetermined uniform tensions. In my copending application Ser. No. 403,191, filed on Oct. 12, 1964, now Pat. No. 3,343,008, granted Sept. 19, 1967, and assigned to the assignee of the present ice invention, I disclose such a filament tension monitoring device.

Although the filament tension monitoring device of my above-cited copending application fulfills the needs outlined above, it has been found in practice to be susceptible at times to slight pulsating fluctuations in tension that are applied to the monitored filament as it unwinds from its spool. These pulsating fluctuations in tension may cause the device to indicate that an excessive or deficient tension is being applied to the monitored filament when in fact such is not the case. An analysis of this condition indicates that the pulsating tension fluctuations cause the rotatable armature of the device of my copending application to oscillate slightly back and forth. When the period of these oscillations approaches the period of the pulsating tension fluctuations, a resonate condition is created whereby the amplitude of the oscillations made by the armature increases to such an extent that one or the other of the associated electrical circuits of the device closes to give a false indication that an incorrect tension is being applied to the monitored filament.

SUMMARY OF THE INVENTION The above-described needs are fulfilled and concomitantly the aforementioned difiiculty of the filament tension monitoring device of my above-cited copending application is eliminated in an illustrative embodiment of a filament tension monitoring device in accordance with the present invention which comprises an electromagnetic toggle switch energizable from a controllable source of potential to provide two stable positions for its armature. The armature is switched from its first stable position to its second stable position by the application thereto of a predetermined external force provided by a component of the force of the tension applied to a monitored filament. As long as the tension applied to the monitored filament is maintained below a preselected maximum value, as determined by the current flow through the electromagnet of the toggle switch, the armature of the toggle switch will remain at its first stable position. When the tension applied to the monitored filament exceeds the preselected value, the armature of the toggle switch will switch to its second stable position and complete a first electrical circuit which actuates an alarm and/or a stop motion device.

It is an aspect of the invention that the allowable maximum tension for which a filament is to be monitored is preselectable by the operation of a simple remote electrical control which determines the current flow through the electromagnet of the toggle switch. This advantageously permits a large number of the filament tension monitoring devices of the present invention to be simultaneously controlled by the same remote control to preselect the same desired tension for which a large number of filaments are to be monitored. This facilitates a simultaneous change in all of the devices and eliminates the necessity for individual adjustment when the type or size of filament is changed.

In accordance with still another aspect of the invention the force which switches the armature of the toggle switch to its second stable position is obtained from the torque applied to a longitudinal filament guide arm by a component of the force of the tension applied t0 the monitored filament. The arm is mounted for rotational movement about a transverse axis intermediate its ends. The filament to be monitored is passed through filament guides on the arm such that the tension of the moving filament applies a torque to the arm tending to rotate the arm in a clockwise direction. The arm is free to rotate a predetermined distance until it contacts the armature of the toggle switch whereupon the clockwise torque of the arm is applied to the armature in the directon required to switch the armature to its second stable position. When the tension applied to the monitored filament exceeds the predetermined allowable maximum value, the force of the clockwise torque will exceed the force required to switch the armature of the toggle switch and the above-described switching actio will occur.

It is also an aspect of the invention, that the rotatable filament guide arm is counterweighted so that in the absence of a clockwise torque applied thereto by the monitored filament a counterclockwise torque is applied to the arm to rotate it counterclockwise to a position where a second electrical circuit is completed to actuate an alarm and/or stop motion device. This advantageously enables the tension monitoring device of the present invention to monitor for filament breakage and deficient filament tension as well as for excessive filament tension.

As long as the clockwise torque applied to the rotatable filament guide arm by a monitored filament is greater than the counterclockwise torque applied thereto by the counterweight, the arm will be rotated clockwise until it contacts the armature of the toggle switch and the above-described second electrical circuit will remain open. Similarly as long as the force of this clockwise torque acting on the armature is less than the predetermined force required to switch the armature from its first to its second stable position, the first electrical circuit described above will remain open. Because the armature of the toggle switch is normally maintained at its first stable position durring a filament monitoring operation, it cannot oscillate in response to pulsating fluctuations in tension applied to the monitored filament and hence the aforementioned problem of the filament tension monitoring device of my above-cited copending application is eliminated.

DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation view of an illustrative embodiment of a filament tension monitoring device in accordance with the present invention and, shows the relative position of the armature of the electromagnetic toggle switch and the longitudinal filament guide arm when a filament breakage or loss of filament tension has occurred.

FIG. 2. is a partial view of the filament tension monitoring device of FIG. 1 and shows the relative position of the armature of the electromagnetic toggle switch and the filament guide arm when the tension applied to the monitored filament is within the predetermined range se-' lected for the particular size and type of monitored filament.

FIG. 3 is a partial view of the filament tension monitoring device of FIG. 1 and shows the relative position of the armature of the electromagnetic toggle switch and the filament guide arm when the tension applied to the monitored filament exceeds the predetermined maximum value selected for the particular size and type of monitored filament.

DETAILED DESCRIPTION The illustrative embodiment of a filament tension mnitoring device in accordance with the present invention as shown in the three operational positions of FIGS. 1 through 3 comprises an electromagnetic toggle switch and a longtiudinal rotatable filament guide arm 12 which controls the switching action of toggle switch 10 from a filst stable position to a second stable position in response to an excessive tension applied to a monitored filament 11.

Toggle switch 10 comprises an electromagnet 13 mounted on a U-shaped coil bracket 14 made of magnetic material and an armature 15 also made of magnetic material. The upper end of electromagnet 13 is secured to a support bracket 16 made of nonmagnetic material which extends between the legs of the U-shaped coil bracket 14 and is secured thereto by suitable screws as shown in FIG. 1. Bracket 16 has a pair of spaced apart supports 16s (one of which is shown broken away) projecting upwardly from bracket 16 to provide support for hinge pin 17. Armature 15 and filament guide arm 12 are mounted on pin 17 in a manner known in the art for independent rotational movement thereabout. The legs of U- shaped coil bracket 14 provide low reluctance magnetic flux paths from the bottom of electromagnet 13 to opposite ends of armature 15. The ends of the legs of bracket 14 form respective pole pieces 14[ and '14r which cooperate with armature 15 to provide the two stable positions of toggle switch 10.

When switch 18 is closed, electromagnet 13 is energized by current flowing from voltage source 19 through potentiometer 20 over electrical conductors 21 and 22. The energization of electromagnet 13 generates magnetic flux which extends from the bottom of electromagnet 13 through coil bracket 14, pole pieces 14l and 14r, armature 15 to the top of electromagnet 13 and establishes the two stable positions for armature 15. The first stable position is with armature 15 rotated counterclockwise until its left-hand end as shown in FIG. 1 and FIG. 2 is adjacent pole piece 14!. The second stable position is with armature 15 rotated clockwise until its right-hand end as shown in FIG. 3 is adjacent pole piece 142'. The magnetic flux extending through pole pieces 14l and armature 15 establishes a magnetic couple therebetween which resists any torque tending to rotate armature 15 clockwise. Similarly the magnetic flux extending through pole piece 14r and armature 15 establishes a magnetic couple therebetween which resists any torque tending to rotate armature 15 counterclockwise. As will be described hereafter armature 15 will reside at the first stable position, shown in FIG. 1 and FIG. 2, when a loss of filament tension occurs and during normal filament monitoring operation, respectively. As will be described later when an excessive tension is applied to monitored filament 11, armature 15 will be switched to and reside at the second stable position as shown in FIG. 3.

Filament guide arm 12 is made of non-magnetic material and as shown in FIG. 1 is mounted on hinge pin 17 for rotational movement thereabout independent of the movement of armature 15 within predetermined limits as will be described. Filament 11, the tension of which is to be monitored, is threaded through a pair of filament guides 12l and 12;- mounted in upright projections of filament guide arm 12 and moves from left to right as shown in FIG. 1. Filament 11 is directed into guide 12l and away'from guide 121' at predetermined angles such that a component of the tension applied to filament 11 will apply a clockwise torque to filament guide arm 12. A counterweight 12w is secured to the left-hand end of filament guide arm 12 so that in the event of a loss of tension or filament breakage guide arm 12 will rotate counterclockwise to the position shown in FIG. 1.

Mounted on the left-hand side of filament guide arm 12 is an electrical contact 12a which extends through a hole 15k in armature 15' to make with a mating contact 16a mounted on coil bracket 16 when filament guide arm 12 is rotated to its extreme counterclockwise position as shown in FIG. 1. Mounted on the right-hand end of armature 15 is an electrical contact 15b which makes with a mating contact 16b mounted on coil bracket 16 when armature 15 is switched to its second stable position as shown in FIG. 3. Contacts 16a and 1612 are connected to an electrical conductor 23 which extends to an alarm circuit 24 and a voltage source 25 and via conductor 26 to a drive control circuit (not shown) which controls a stop motion device. When contact 12a makes with its mate contact 16a as shown in FIG. 1, ground potential is applied from coil bracket 16 through filament guide arm 12 and closed contacts 12a and 16a to operate alarm 24 and the drive control circuit. Similarly when contact 1511 makes with contact 16b as shown in FIG. 3, ground potential is applied from coil bracket 16 through armature 15 and closed contacts 15b and 16b to operate alarm 24 and the drive control circuit.

Secured to the left-hand leg of coil bracket 14 by suitable screws as shown in FIG. 1 is a mounting bracket 27 made of non-magnetic material. Bracket 27 may be utilized in any manner known in the art to secure the fila ment tension monitoring device of my invention to a suitable supporting frame (not shown). Extending through a threaded hole 27a in bracket 27 as shown in FIG. 1 is an adjusting screw 28 which controls the width of the air gap between armature 15 and pole piece 14l when armature 15 is at its first stable position as shown in FIG.

1. The purpose of controlling this air gap will be described hereafter.

DESCRIPTION OF OPERATION The operation of the illustrative embodiment of a filament tension monitoring device in accordance with the present invention as shown in the drawing will now be described. Prior to the application of tension to monitored filament 11, filament guide arm 12 will reside at its, extreme counterclockwise position as shown in FIG. 1 due to the counterclockwise torque applied thereto by counterweight 12w. This counterclockwise torque applied to filament guide arm 12 also causes armature 15 to rotate counterclockwise until it contacts the end of adjusting screw 28 because filament guide arm 12 contacts armature 15 at point X as it rotates counterclockwise. Accordingly, when switch 18 is closed and electromagnet 13 is energized, a magnetic couple will be established between armature 15 and pole piece 14l which causes armature 15 to reside in its first stable position. The strength of this magnetic couple is determined by the setting of potentiometer 20 which controls the current flow through electromagnet 13.

When tension is applied to monitored filament 11 a component of the tension applies a clockwise torque to filament guide arm 12. When this clockwise torque exceeds the counterclockwise torque applied thereto by counterweight 12w, filament guide arm 12 will rotate clockwise until it contacts armature 15 at point Y as shown in FIG. 2. With this rotation of filament guide arm 12, contacts 12a and 16a open the electrical circuit to alarm 24 and to the drive control circuit. As long as the tension applied to filament 11 is of such a value that the resulting clockwise torque applied to filament. guide arm 12 exceeds the counterclockwise torque applied thereto by counterweight 12w, contact pair 12a and 16a will remain open and alarm 24 and the stop motion device controlled by the drive control circuit over lead 26 will not be operated. counterweight 12w is advantageously selected so that a predetermined minimum tension, 2 grams for example, must be continuously applied to monitored filament 11 to prevent operation of alarm 24 and/ or the stop motion device.

As long as the tension applied to monitored filament 11 exceeds the predetermined minimum value the relative position of filament guide arm 12 and armature 15 will be as shown in FIG. 2 and contact pair 12a and 16a will remain open. In the event of a breakage of filament 11 or a reduction in the tension applied thereto be-' low the predetermined minimum value, filament guide arm 12 will rotate counterclockwise to the position shown in FIG. 1 and contact pair 12a and 16a will close to complete the electrical circuit to alarm 24 and to the drive control circuits to operate a stop motion device. Thus the filament tension monitoring device of my present invention advantageously monitors for filament breakage and loss of tension.

During normal tension monitoring operation with filament guide arm 12 in contact with armature 15 at point Y as shown in FIG. 2, the clock-wise torque applied to filament guide arm 12 by a component of the tension applied to monitored filament 11 is transferred to armature 15 and attempts to rotate armature 15 in a clockwise direction. This clockwise torque applied to armature 15 is resisted by the force of the magnetic couple established between armature 15 and pole piece 141. When the force resulting from the clockwise torque applied to armature 15 by filament guide arm 12 exceeds the force of the magnetic couple resisting this torque, armature 15 is switched to its second stable position adjacent pole piece 14r as shown in FIG. 3. When armature 15 switches to its second stable position contact pair 15b and 16th close and complete the electrical circuit to alarm 24 and the drive control circuit to operate a stop motion device. Armature 15 is held in the second stable position as shown in FIG. 3 by the magnetic couple established between armature 15 and pole piece 14r. After the excessive tension condition is corrected by an operator, the armature 15 may be returned to its first stable position by momentarily de-energizing electromagnet 13 or by physically switching armature 15 to its first stable position by pushing downwardly on filament guide arm 12.

The maximum tension permissible for different types or sizes of filaments is advantageously selected in accordance with my invention by the operation of potentiometer 20. This controls the strength of the magnetic couple established between armature 15 and pole piece 14l. For example, the maximum allowable tension for a particular filament may be 15 grams. Potentiometer 20 is adjusted such that when a 15 gram tension is applied to the monitored filament the force of the clockwise torque applied to filament guide arm 12 and armature 15 will exceed the force of the magnetic couple between armature 15 and pole piece 141 resisting this torque and armature 15 will switch to its second stable position.

As long as the tension applied to a monitored filament 11 is maintained above a predetermined minimum value, 2 grams for example, and below the preseleted maximum value, 15 grams for example, filament guide arm 12 and armature 15 will remain positioned as shown in FIG. 2 and the electrical circuit to alarm 24 and the drive control circuit will not be completed. Filament guide are 12 is free to rotate slightly in response to fluctuation in tension within the predetermined range 'without operating alarm 24. However, any decrease in tension below the predetermined minimum or any increase in tension above the preselected maximum will result in the operation of alarm 24 and/ or the drive control circuit which actuates the stop motion device.

Although a single lead 23 is shown extending from contacts 16a and 16b to alarm 24 in FIG. 1, it is understood that separate leads extending to individual alarms may be utilized to provide a separate alarm for deficient tension or filament breakage and for excessive filament tension.

Because the filament tension monitoring device of my present invention is electrically controlled from potentiometer 20 to preselect a desired maximum monitoring tension, the device may advantageously be simultaneously controlled with a plurality of like devices from the same remote control. Accordingly, a large number of devices of the present invention may be simultaneously adjusted to monitor for the same maximum allowable tension. This may advantageously be accomplished by connecting the toggle switches 10 of the devices in parallel to same po tential source 19, potentiometer 20 and switch 18 as indicated in FIG. 1. In a similar manner the lead 23 from contact 16b of each device may be connected in parallel to the same alarm 24 and drive control circuit as indicated in FIG. 1 or may extend to individual alarm circuits.

To facilitate the control of a large number of filament tension monitoring devices of the present invention from a single remote electrical control such as potentiometer 20 and concomitantly ease the manufacturing requirements of the devices, each is provided with an adjusting screw 28 which controls the width of the air gap between armature 15 and pole piece 141. By controlling the width of this air gap the strength of the magnetic couple therebetween is also controlled. This permits a large number of the devices to be initially adjusted or trimmed to respond uniformly to the same current supplied by a potential source. In this manner manufacturing tolerances may be less stringent yet uniform operation obtained.

It is to be understood that the above-described embodiment is illustrative only of the principles of the present invention. Numerous other arrangements may be devised by those skilled in the art without departing from the spirt and scope of the invention.

What is claimed is:

1. In a filament tension monitoring device the combination comprising an electromagnetic toggle switch comprising a longitudinal armature mounted for rotational move ment about a transverse axis intermediate the ends thereof, a pair of pole pieces positioned adjacent respective ends of said armature, and

means for establishing magnetic couples between the ends of said armature and the respective pole pieces to provide a first stable position and a second stable position, counterclockwise and clockwise respectively, for said armature,

means for setting said armature to its first stable position when a filament tension monitoring operation is initiated, and

means responsive to the tension applied to a monitored filament and operative when a preselected maximum tension is applied thereto for applying a mechanical force to said armature to switch it from its first to its second stable position.

2. The combination defined in claim 1 further comprising an alarm, and

means responsive to the switching of said armature to its second stable position for operating said alarm.

3. The combination defined in claim 2 further comprising means controlled by said means responsive to the tension applied to said monitored filament and operative when said armature is at its first stable position and the tension applied to said monitored filament falls below a predetermined minimum for operating said alarm.

4. The combination defined in claim 3 further comprising means for controlling said toggle switch to preselect said maximum tension required to be applied to said monitored filament to cause said means responsive to said tension to switch said armature to its second stable position.

5. The combination defined in claim 4 wherein said means for establishing magnetic couples between the ends of said armature and the respective pole pieces comprises an electromagnet, and

means for energizing said electromagnet.

'6. The combination defined in claim 5 wherein said means for controlling said toggle switch to preselect said maximum tension comprises means for controlling said energizing means to preselect the strength of said magnetic couples.

7. The combination defined in claim 6 wherein ,said means responsive to the tension applied to a monitored filament comprises i -a longitudinal arm mounted for rotational movement about a transverse axis intermediate its ends, 7

means responsive to a component of the tension applied to said monitored filament for applying a clockwise torque to said arm, and e means for applying the force of said torque to said armature to switch said armature from its stable counterclockwise position to its stable clockwise position. e r

8. The combination defined in claim 7 wherein said means forsetting said armature to its first stable position comprises means for applying a predetermined counterclockwise torque to said arm, and i means operative in the absence of tension applied to said filament for applying the force of said counterclockwise torque to said armature to rotate it to'its stable counterclockwise position.

9. In a filament tension monitoring device the combination comprising an electromagnetic toggle switch comprising an armature, at least one pole piece, and means for establishing a magnetic couple between said armature and said pole piece to provide first and second stable positions for said armature, means operative in response to the absence of a tension applied to a monitored filament for applying a mechanical force to said armature setting it to its first stable position, means responsive to tension applied to said monitored filament and operative when said tension exceeds a predetermined value for applying a mechanical force to said armature setting it to its second stable position, and means for varying the strength of said magnetic cou;

ple to vary said predetermined value of tension operative to set said armature to its second stable position.

References Cited UNITED STATES PATENTS 1,364,944 1/1921 Mclnnerneyv 335-161 3,227,833 1/1966 Davies et a1. -1 200-61.18 X 3,253,269 5/1966 Ratti 340-259 3,260,823 7/1966 McClellan 335-161 FOREIGN PATENTS 286,836 3/ 1928- Great Britain.

DONALD J. YUSKO, Primary Examiner P. PALAN, Assistant Examiner US. Cl. X.R. 

